I respectully disagree that the format has any issues at all. In fact, the format is so mature that those who feel that they have to improve it to justify their existence are trying to shoehorn more and more useless crap in to it, to make it more like a multi-media web page (yeah, I'm looking at you, EPUB3).

You know, I'm a serial lurker and really shouldn't go controversial in my very first post, but ... I'm not into introductions and have to disagree. I actually think there isn't a single layer of the whole ebook publishing format (meaning as in "channel format"[1]) which doesn't have issues.

Competing open and proprietary file formats, built on top of ever-changing standards, with multiple proprietary drm schemes and mathematical typesetting somehow quirked on--that's a makeshift solution. It undoubtedly works and is fine for volatile media, but I'm not so sure it's adequate for books, which tend to outlast the average twitter junk of the day. Slightly.

On the device side: limited support for proper microtypography, not even trying to avoid cardinal sins like widows and orphans. The result is readable, but very little else. The dead tree books are far more refined. Doesn't mean I don't like ebooks, just that some minor flogging in the right places might improve the experience.

Worse, it's in the publishers' best interest to "enrich" content, because static text is just sooo hard to sell to the masses. Given your obvious love for epub3, I suspect you might agree this is an upcoming issue with the ebook publishing format, especially with the brick and mortar type publishers slowly going extinct. For bibliophiles, anyway.